Bicycle Day 🚲

Overview

Bicycle Day, celebrated annually on April 19th, commemorates the first intentional acid trip by Swiss chemist Albert Hofmann in 1943. After self-administering what he believed to be a small dose of lysergic acid diethylamide (LSD-25) in his laboratory, Hofmann experienced its profound psychoactive effects while cycling home, accompanied by his assistant. This pivotal event marked the discovery of LSD's psychedelic properties and is widely recognized as a significant moment in the history of psychedelic research and counter-culture.

Origin and story

Albert Hofmann first synthesized LSD-25 in 1938 while researching ergot alkaloids, but its psychoactive effects were not discovered until his 1943 self-experiment.

Hofmann's self-administered dose on Bicycle Day was 250 micrograms, an amount he believed to be a threshold dose, but is actually a significant dose of LSD.

Quick facts

• DateApril 19
• TypeCultural / community observance
• Great forFriends, Families, Classrooms, Teams

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Ways to celebrate

• Take an actual bike ride today, as a literal nod to how the day got its name.
• Read about Albert Hofmann's 1943 self-experiment and his now-famous bicycle ride home — the origin of "Bicycle Day."
• Learn how LSD-25 was first synthesized back in 1938, five years before its effects were even discovered.
• Talk about the disconnect between what Hofmann thought was a cautious "threshold dose" (250 micrograms) and how strong it actually turned out to be.
• Look into the modern psychedelic-research renaissance happening in labs today, decades after Hofmann's discovery.

Learn more

• This Bicycle Day, Celebrate Albert Hofmann's Psychedelic Discovery (Rolling Stone)

Fun facts

• Albert Hofmann first synthesized LSD-25 in 1938 while researching ergot alkaloids, but its psychoactive effects were not discovered until his 1943 self-experiment.
• Hofmann's self-administered dose on Bicycle Day was 250 micrograms, an amount he believed to be a threshold dose, but is actually a significant dose of LSD.
• The first public celebration of 'Bicycle Day' was organized by Thomas B. Roberts, a professor at Northern Illinois University, in 1985, decades after the original event.

Sources and attribution

This Bicycle Day, Celebrate Albert Hofmann's Psychedelic Discovery (Rolling Stone)

External links may lead to third-party websites.

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FAQ

When is Bicycle Day?

It is observed on April 19 each year.

What is Bicycle Day?

Bicycle Day, celebrated annually on April 19th, commemorates the first intentional acid trip by Swiss chemist Albert Hofmann in 1943. After self-administering what he believed to be a small dose of lysergic acid diethylamide (LSD-25) in his laboratory, Hofmann experienced its profound psychoactive effects while cycling home, accompanied by his assistant. This pivotal event marked the discovery of LSD's psychedelic properties and is widely recognized as a significant moment in the history of psychedelic research and counter-culture.

How do people celebrate Bicycle Day?

Take a literal bike ride, or read about April 19, 1943 — the day chemist Albert Hofmann first experienced LSD's effects and famously rode his bicycle home.

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